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Morphology and arrangement of meromes in Ischadites dixonensis, an Ordovician Receptaculitid


Published 1978
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Ischadites dixonensis (Miller and Gurley, 1896), from the Ordovician Galena Group of Illinois, is the oldest described North American ischaditid. The holotype is exceptionally well preserved and provides information on merome head morphology, articulation, and arrangement on the surface of the thallus. Meromes occur in whorls and form an equal number of dextral and sinistral parastichies. Each parastichy begins either at one of the heads surrounding the basal pole or at a triangulum, and extends to the margin of a clearly demarcated apical lacuna. The unusually complete morphological characterization that is now available for I. dixonensis will play an important role in discussions of receptaculitid morphogenesis and orientation

Includes bibliographical references (p. 31)

Ischadites dixonensis (Miller and Gurley, 1896), from the Ordovician Galena Group of Illinois, is the oldest described North American ischaditid. The holotype is exceptionally well preserved and provides information on merome head morphology, articulation, and arrangement on the surface of the thallus. Meromes occur in whorls and form an equal number of dextral and sinistral parastichies. Each parastichy begins either at one of the heads surrounding the basal pole or at a triangulum, and extends to the margin of a clearly demarcated apical lacuna. The unusually complete morphological characterization that is now available for I. dixonensis will play an important role in discussions of receptaculitid morphogenesis and orientation

Fieldiana series has been published as Geological Series by Field Columbian Museum (1895-1909) and Field Museum of Natural History (1909-1943), and as Fieldiana: Geology by Chicago Natural History Museum (1945-1966) and Field Museum of Natural History (1966-)


Volume Fieldiana, Geology, Vol.39, No.2
Publisher Chicago : Field Museum of Natural History
Pages 28
Possible copyright status In copyright. Digitized with the permission of the Chicago Field Museum. For information contact dcc@library.uiuc.edu.
Language English
Call number 261074
Digitizing sponsor University of Illinois Urbana-Champaign
Book contributor University of Illinois Urbana-Champaign
Collection biodiversity; fieldiana

Full catalog record MARCXML

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